(1) Field of the Invention
This invention relates to improvements in and relating to the ophthalmoscope to be used by oculists and physicians for intraocular inspection or observation.
(2) Description of the Prior Art
The intraocular inspection or observation has a great important in ophthalmological and internal examinations. In this connection, however, it is an usual experience that the conventional fundus camera or other ophthalmoscopic instrument which employs a single light source for transillumination is met by various difficulties during the inspection due to the peculiar optical characteristics of the eye. For example, in the case of inspection by a fundus camera, in order to make a full observation from the aspect of the illumination and observation systems, it becomes necessary to increase the intensity of transilluminant light from the single light source. However, on the contrary, the increase of the illumination light intensity increases the light reflections on the eyeball and as a result the observation is considerably obstructed by the reflected light. Therefore, there have thus far been made various technical improvements and proposals in connection with the fundus camera for attenuating the reflected light but none of them succeeded in arriving definite technical solutions to the above-mentioned problems, projecting excessive light into the patient's eye and failing to reply to the oculists' strong demand for improvements in this regard. On the other hand, the directoscope which exists also as an ophthalmoscopic instrument involves the same difficulties as the fundus cameras in principles, and at the present moment still has a number of technical problems yet to be solved.
Further, the so-called slit lamp microscope which is resorted to for intraocular observation is a system in which a light ray is projected through a slit lamp to form a narrow light ray. In this case, there is also a problem that, if the breadth of the light ray is broadened, the light reflection from the eye-ball becomes stronger and the image of the observing portion is blurred, in addition to problems in the operational aspect which need solutions.